There is a known musical piece reproducing system of related art that causes a display device to display a motion graphic in synchronization with reproduction of a musical piece. There is also a known information processing system of related art that calculates importance of each word contained in lyrics and causes a display device to display an image of letters out of the lyrics in such a way that the higher the importance of the word, the larger the letter image corresponding to the word (see Patent Literature 1, for example). A technology of adding an animation to a letter image to be displayed is also known.